As what had been acknowledged, the current patent of common size and structure adjustable wrench sleeves such as U.S. Pat. No. 6,374,710 is using the retractable effect of a plurality of pillar posts mounted inside the sleeve to match with varieties of specifications of work pieces. The structure is more than complicated, quite a number of elements (such as sleeve 1, pillar post 3, retaining rod 4 and retraction spring 5) are required and necessary to be accommodated into sleeve 1, which needs higher cost in manufacturing and is presumed inconvenient to use because aligning is required when using it.
U.S. Pat. Nos. 1,471,451 and 3,698,267 are also about couplings of varieties of specifications, which are similar concept in structure design to the above-mentioned U.S. Pat. No. 6,374,710 and bear the same shortages in use. U.S. Pat. No. 2,387,339 and No. 4,608,887 are sockets with complicate threaded structure and clamp the workpiece by radial and axial movement. And U.S. Pat. No. 5,927,160 has no the function for matching with varieties of scales of work pieces.